Thermal aerosol dispenser



Jan. 22, 1963 H. D. JOHNSON ETAL 3,074,199

THERMAL AEROSOL DISPENSER Original Filed May 16, 1960 JNV TORS HAROLD D.NSON BY Rosamw. HNSON )h-e M14 mu +01%,

- A'r'rvs United States Patent 3,074,199 Tl-ERMAL AERGSGL DlSlENSERHarold D. Johnson and Robert W. Johnson, Ciearwater,

Fla., assignors to General Implement Corporation,

Clearwater, Fla, a corporation of Florida Continuation of applicationer. No. 29,43, May 16,

1960. This application Apr. 1", E61, 5er. No. 101,533 12 (Ilaims. {CL43-129) The present invention relates to aerosol dispensers and moreparticularly to a self-contained, hand held dispenser of the thermaltype for vapon'zing liquid aerosol insecticides or the like.

In the controlling of insects, for example mosquitoes, it has been foundeffective to generate a fog consisting of minute droplets convenientlyreferred to as an aerosol. It is common practice to create an aerosol,for insect control purposes, by dissolving an insecticide, for exampleDDT, in a vaporizable mineral oil, or mixture of oils, heating the sameto such high temperature that vaporization occurs. Devices foraccomplishing this on a commercial scale have been designed; however,they are usually heavy and cumbersome, in many cases truck-mounted. Itis a common practice, in vaporizing the oil, to mix the liquid aerosolwith the products of combustion from the heat source so as to utilize alarge proportion of the available heat. However, this tends to bringabout harmful chemical reactions, particularly where the temperature isallowed to become excessive. Because of various operating difiiculties,aerosol dispensers capable of high output are generally operated bycommercial services or municipalities and under the control of a trainedoperator.

It is an object of the present invention to provide a portable aerosoldispenser of the thermal type capable of producing a fog having maximumeffectiveness, with an optimum range of droplet size, and which permitsgeneration of a dense fog insuring effective concentration in the spacebeing treated While avoiding wasteful precipitation. It is anotherobject to provide a portable aerosol dispenser in which the insecticide,or similar additive, is maintained fully effective and which avoids thedeterioration to which such additives are subjected in dispensers ofconventional design, either because of excess temperature or as a resultof mixing with the products of combustion from the heat source. Thispermits use of relatively unstable but effective agents not usable orpractical heretofore. More specifically, it is an object to provide anaerosol dispenser having a vaporizing coil in which the aerosol materialis continuously vaporized from the liquid form but which neverthelessavoids destructive overheating as might be caused, for example, byobstructing the flow or by the existence of hot spots along the path offlow. On the contrary it is an object to provide an aerosol dispenser inwhich the temperature of the aerosol is progressively increased to thevaporization range, and with the temperature reaching a maximum justprior to discharge so as to avoid destructive superheating of thegenerated fog or vapor.

It is another object of the invention to provide an aerosol dispenserwhich, although portable and compact, nevertheless has a highheat-producing capability and which is able to produce fog or vapor at arate which characterizes much larger, truck-transported apparatus. it isa further object in this connection to provide an aerosol dispenserwhich not only has a high production rate but which has a highetliciency as measured in cubic feet of fog per gallon of liquid used toproduce the aerosol and which may be referred to for convenience asaerosol liquid. It is a related object to provide an aerosol dispenserof the above type which is capable of being held,

by a convenient pistol grip, in one hand of the operator for easymanipulation. It is also an object to provide an aerosol dispenser whichis not only light and compact but which has a comfortable feel and whichmay be held, where necessary, for long periods of time without fatigue.

it is another and related object to provide an aerosol dispenser whichis not limited to use in the open air but which may be easily carriedinto buildings and other confined locations. The device is characterizedby an elongated discharge nozzle which may, in fact, be thrust intocracks and openings containing, or suspected to contain, insect life. Inthis way the spaces between walls, the spaces between the ceiling andthe floor above etc. may be treated with an exceedingly high fogconcentration of insecticide or other agent.

It is yet another object to provide an aerosol dispenser which is notonly easy to carry about but which does not require adjustment and whichmay be successfully used without any prior experience. Thus to put thedevice into operation, the fuel gas is simply turned full on withoutnecessity for throttling adjustment. In this connection it is an objectto provide an aerosol dispenser having a self-contained source of fuelgas under pressure and a self-contained source of aerosol liquid withprovision for automatically controlling the rate of liquid flow and forautomatically varying the rate of flow of the liquid in accordance withchanges in the pressure of the gas. Such coordination of the fuel rateand aerosol rate tends to insure that where the device is operatedeither intermittently or over a long period of time the aerosol liquidwill tend to be vaporized to the right degree, with the temperaturebeing neither too high nor too low, without necessity for constantreadjustment of the flow rate. It is also an object to provide anaerosol dispenser which, once the fuel has been lighted, need not beoperated continuously and in which the flow of the aerosol liquid may beturned on and turned oif by a convenient trigger valve during warm-upand to conserve the aerosol while, nevertheless, minimizing the elfectof excessive temperatures during the time when the aerosol is notflowing.

It is still another object related to the foregoing to provide anaerosol dispenser in which the aerosol liquid is progressively heatedand vaporized but which is free of any artificial restriction exceptthat which results from the friction of the aerosol with the interiorsurface of the vaporizing coil so that the vapor is free to pass throughthe unit with a high velocity and minimum obstruction for dischargebefore excessive temperatures are reached.

It is a still further object of the present invention to provide anaerosol dispenser intended to be hand held and capable of employing highheat rates on the order of 25,000 B.t.u. per hour but which has novelcooling 0 provisions permitting operation for long periods of timewithout the device becoming uncomfortable to the operator and withoutany progressive heat buildup in the bandle or other parts of the device.

It is yet another object of the present invention to provide an aerosoldispenser of the thermal, hand held type which is safe to use and whichdoes not require the taking of any special precautions. In operation theflame is simply turned on and the trigger is pressed to permit flow ofthe aerosol liquid into the vaporizing coil. It is a related object toprovide an aerosol dispenser in which the vapor and products ofcombustion are separated by discharging them in dilferent directionsthereby substantially eliminating the risk that the aerosol vapor willcatch fire. Moreover, since the Vapor is isolated from the products ofcombustion, the nozzle may be directed into closed spaces containingcombustibles with out creating a fire hazard.

It is a detailed object of the present invention to provide an aerosoldispenser which is quiet in operation and which avoids the noisypercussion effect of internal combustion type dispensers of about thesame thermal and volumetric capacity. It is another detailed object toprovide an aerosol dispenser which uses readily available fuel (propane)and which is capable of employing oil-based liquid insecticides ofwidely varying composition and obtainable in many instances free ofcharge from municipal insect control authorities.

Finally it is an object of the invention to provide an aerosol dispenserwhich is simple and inexpensive to construct and which requires littleor no maintenance even when operated over long periods of time.

Other objects and advantages of the invention will become apparent uponreading the attached detailed descriptron and upon reference to thedrawings in which:

FIGURE 1 is a perspective of an aerosol dispenser constructed inaccordance with the present invention.

FIG. 2 is a longitudinal section taken through the dispenser of FIG. 1to bring out the details of construction.

While the invention has been described in connection with a preferredembodiment, it will be understood that We do not intend to be limited tothe embodiment shown and intend to cover the various modifications andequivalent constructions which may be included within the spirit andscope of the appended claims.

Turning now to the drawings, an aerosol dispenser 1t? constructed inaccordance with the present invention includes a horizontally arrangedburner tube 11 containing a vaporizing coil 12 having an inlet end 13and a discharge end or nozzle 14. Extending horizontally under theburner tube 11, and spaced from it, is a valve body 15 having a fueltank 15 charged with propane or the like and an aerosol tank 17 chargedwith aerosol liquid, for example, insecticide, suspended below it, sideby side. The tanks are conveniently screwed into the valve body at screwconnections 18, i9. Secured to the valve body and to the rear end of theburner tube is a handle so in the form of a pistol grip, enabling thedispenser to be supported and manipulated by the hand of the operator.

In carrying out the present invention, a burner is provided within theburner tube for heating the vaporizing coil using gas fed from the fueltank 16. In the present instance the burner, indicated at 21, is axiallylocated at the rear end of the tube, being mounted on a burner disc 1 22fitted into the tube and which may be held in place by mounting screws23. Forming a part of the burner nozzle is a threaded insert 25 whichdefines a gas metering orifice. This orifice is in communication with apassage 26 within the handle and a longitudinal passage 27 within thevalve body and which leads to the fuel tank 16. For the purpose ofturning the gas on and oil, a gas valve 30 is provided of a type wellknown in the valve art having a threaded stem terminating in a tip orneedle 31 which seats against a suitable seat in the valve body. Thestem mounts a knob 32 at its outer end.

For the purpose of supplying aerosol liquid to the vaporizing coil 12, adip tube is secured to the valve body so as to extend down to the bottomof the tank 17 and with the upper end of the-tube being preferablythreaded into the valve body. Horizontally bored in the valve body andcommunicating with the upper end of the dip tube is a valve recess orbore 41 having a valve seat 42. Communicating with the bore 41 is apassageway 43 leading to a connection 44 with the inlet end 13 of thevaporizing coil. In order to control the flow of the aerosol liquid intothe vaporizing coil, a valve plunger having a stem or tip 51 is fittedinto the bore 41 for seating on the valve seat 42.

In accordance with one of the aspects of the present invention, atrigger operator is provided for the valve plunger 50 associated withthe pistol grip 23. Such operator is in the form of an elongated triggeran pivoted on a pin 61 and engaging a neck 62 formed on the rear end ofthe valve plunger 50. In order to bias the valve plunger and triggerforwardly into the valve-seated position, a biasing spring 63 containedwithin a bore 64 in the handle presses against the end of the valveplunger. Pulling upon the trigger 6t} retracts the valve plunger fromthe seat 4-2 to permit fiow of the aerosol liquid from the tank 17 intothe inlet end of the vaporizing coil. The arrangement is such that thetrigger is pulled when the pistol grip is held in the normal way.

Further in accordance with the present invention, means are provided forpressurizing the aerosol liquid and metering the same in accordance withthe pressure of the gas supplied to the burner so that the pressureapplied to the aerosol liquid varies in accordance with the variationsin gas pressure. Thus the rate of flow of the aerosol liquid tends tovary with the amount of heat being liberated at the burner withoutnecessity for constant adjustment of the dispenser by the operator. Inthe present instance this is accomplished by the simple expedient ofproviding communication between the gas passageway 27 and the interiorof the aerosol tank 17 and by conducting the liquid from the tankthrough a metering orifice. Thus it will be noted in FIG. 2 that avertical connection 79 is made, by drilling or otherwise, between thetapped receptacle 1% of the aerosol tank 17 and the gas passage 27.Moreover, a metering orifice '71 is provided in the dip tube. in thepresent instance the metering orifice is located at the bottom end ofthe tube, but it may, if desired, be located elsewhere in the path ofliquid flow, for example, at the top of the tube. For the purpose ofpreventing any escape of gas from the aerosol tank after the gas valve39 is turned off and to cause a pressure diderential between the gaspassage 27 and the tank, a check valve 75 is provided having a poppetwhich is pressed against a seat '76 by a small coil spring 77, having athreaded retainer 73. It will be understood that the spring 77 exerts arelatively light pressure so that the check valve is readily unseated bythe gas pressure which exists in the passageway 27 under normaloperating conditions.

The spring pressure nevertheless is such as to establish a pressuredifferential between the gas line 27 and the tank of aerosol liquid,especially where the line pressure is more than is needed for effectingpressurized flow of the liquid. Adjustment of the spring by the retainer78 provides a convenient means of adjusting fluid flow, other factorsbeing held constant.

It will be apparent, then, that Whenever the gas control valve 3t? isturned on to supply gas to the burner, gas pressure is applied to thesurface of the liquid aerosol tending to force the aerosol through themetering orifice 71, up the dip tube 40' and through the vaporizing coil12 at a rate which depends upon the gas pressure. At room temperatureliquid propane exerts a pressure of about p.s.i. However, it will beappreciated by one skilled in the art that the pressure of the gas mayvary over rather wide limits with temperature. Thus as the gas is drawnoff, the change of state, from liquid to gaseous, causes the temperatureof the tank to drop which in turn causes the pressure of the gas to belowered by a substantial percentage with consequent reduction of theamount of heat liberated at the burner. A short period of non-use causesthe pressure to be restored to the original value. Turning the device onagain lowers the pressure. Thus it can be seen that liquid propane, orsimilar fuel, is subject to relatively wide pressure variationsparticularly where, as here, the size of the tank is small as comparedto the rate of fuel consumption. As stated, because of the novelcoordination between the liquid and gas pressures, the present deviceenables efiicient vaporization without adjustment regardless of whetherthe device is used constantly or intermittently.

It will be understood that the term vaporization is used herein in ageneral sense to denote conversion from the liquid state, not into gas,but rather into the form of fine droplets or fog. The selection of theproper orifice 71 is a matter well within the skill of the art, theorifice being simply increased or decreased, maintaining all of theother parameters constant, until the droplet size is optimum, say,within the range of -12 microns. Too high a rate of fiow of aerosolliquid results in insufficient vaporization and the production of largedroplets which are inefiicient and wasteful, while too small a flowproduces over-vaporization or gasification with the result that theparticles are too small to be effective. Once the proper diameter oforifice is established it can be used without change until theconditions are changed in some substantial respect, as, for example, byswitching to a radically different aerosol.

In accordance with one of the aspects of the present invention thepresent device is constructed so that the valve body and the pistol gripparticularly the latter, are maintained at .a safe and comfortabletemperature even when the dispenser is used over a long period of timeand in spite of the large amount of heat liberated by the burner 21.This is accomplished in part by minimizing the heat conductive pathbetween the burner tube and the pistol grip and by providing betweenthem openings for aspirating the burner air. Thus in the presentinstance there is provided a relatively narrow stem or neck 8i} having aplurality of radially directed aspirating openings $1 through which airis drawn by venturi action into the stream of gas. Since a substantialamount of air is required for combustion, this provides an effectivebarrier to direct heat flow from the burner tube. In order to provideadditional cooling effect, the valve body 15 and the pistol grip orhandle 20 are thermally coupled together and made of good conductingmetal such as aluminum so that the change of state of the fuel fromliquid to gaseous is effectively utilized to cool both the valve bodyand the hmdle. It will, moreover, be understood that passage of therelatively cool aerosol liquid from the tank 17 through the passage 43of the valve body provides a cooling effect.

For the purpose of minimizing direct heat conduction from the burnertube to the valve body, the two are largely isolated from one another.Thus the mounting pad 85 used at the front end of the valve body is oflimited cross section, sufficient only to provide the necessarymechanical strength and rigidity. It may be noted that such pad, beinglocated at the extreme front end of the valve body, is closely adjacentthe point of connection 18 of the gas tank to so that the heattransmitted by the pad is locally absorbed by the change of state of thegas, with little left over to reach the pistol grip. The heat which istransmitted through the pad 85', in fact, performs a useful purpose tothe extent that it tends to counteract wide swings in the temperature ofthe tank 16, hence keeping the gas pressure more nearly constant. Thecoil itself is not efifective to conduct heat to the valve body atconnection 44 since it is constantly cooled by the aerosol liquid.Because of the above, the aerosol dispenser may be operated comfortablyon a continuous basis at extremely high heat rates on the order of25,000 Btu. per hour.

Not only is the pistol grip maintained at a relatively low temperature,but also the device includes novel provision for preventing overheatingof the burner tube itself. Thus it will be noted in the drawings thatthe vaporizing coil has an initial set of helical convolutions 91 at theinlet end which are such diameter as to be closely adjacent the insideWall burner tube with good thermal coupling with the wall of the tube.It will therefore be apparent that, notwithstanding the liberation of alarge amount of heat within the burner tube, the relatively cool aerosolliquid flowing through the initial convolutions $1 tends to maintain thetube at a lower temperature than would otherwise be possible. This tendsto reduce the hazard of igniting something combustible by inadvertentcontact with the wall of the tube. Preferably the inlet portion of thevaporizing coil, which is subjected to the major cooling action of theentering liquid, is located at the rear end of the tube and closelyadjacent the handle of the device.

In accordance with one of the most important aspects of the presentinvention, means are provided for maintaining the products of combustioncompletely separate from discharged fog or effluent flowing from thevaporizing coil, with the products of combustion being discharged in onedirection, for example, through vents provided at the top of the burnertube while the efilueut is discharged in another direction, for example,forwardly through a discharge nozzle which extends some distance awayfrom the burner tube. Moreover, in accordance with the present inventionthe burner tube has a barrier in the form of a cap at its forward endwhich is axially penetrated by the nozzle of the vaporizing coil for thepurpose of providing positive isolation between the combustion chamberand the discharge nozzle. In the present instance the products ofcombustion are discharged through a series of vents 4 formed in theupper side f the burner tube, such vents being preferably in the form ofspaced transverse slots machined in the wall of the burner tube. Suchslots are distributed over a length which is an appreciable portion ofthe length of the outer convolutions 91 of the vaporizing coil so thatall portions of the coil are vented to about the same degree. To isolatethe discharge nozzle 14, a barrier or end cap is provided at the forwardend of the burner tube having a central access opening 101 through whichthe nozzle 14 of the vaporizing coil projects. The cap may be held inplace by means of machine screws M2 or the like. The fit between thevaporizing nozzle 14 and the opening N1 is preferably rather snug sothat the nozzle is effectively sealed. As a result of the isolation thusprovided there is no possibility that the efiluent will becomecontaminated by the products of combustion or that chemical reactionswill occur with the products of combustion at the high temperature sothat the insecticide or other aerosol is maintained at fulleffectiveness. Moreover, the point of discharge is sufficiently removedfrom the region of high temperature so that there is little or nopossibility that the efiiuent will inadvertently catch fire which, whilenot, of itself, dangerous, may nevertheless be startling to the user andmight cause him to drop the dispenser to create a fire hazard.

In accordance with one of the aspects of the present invention, a secondor inner set of convolutions is provided in the vaporizing coilterminating in an axial, straight run portion leading to the dischargenozzle 14 of the coil. Thus, referring to FIG. 2 it will be noted thatthe outer convolutions 91 are integrally joined to a set of helicalinner convolutions 92 which are in a. folded back relation with respectto the convolutions 91 and which lie in a position to be directly actedupon by the flame, and to some extent to confine the flame whichproceeds from the burner 26). The inner convolutions 92 are joined to acentral, straight run of tubing 93. The tubing forming the vaporizingcoil is preferably in one piece having a constant diameter all the wayfrom the inlet end 13 to the discharge end 14. It is found that such anovel arrangement of vaporizing coil produces progressive heating andprogressive vaporization of the aerosol liquid, with the coil being freeof any artificial restriction so that the aerosol may proceed throughthe coil uninterruptedly and at a velocity which depends upon a numberof factors including the inlet pressure and the friction to fluid fiowprovided by the inner walls of the coil. With regard to the progressiveheating of the aerosol, it will be noted that the inlet end 13 and thefirst few convolutions 91 are in a relatively cool position so that theaerosol liquid is gradually brought up to a temperature where vaporizingcommences without any possibility of sudden and unwanted flashing. Asthe aerosol continues its passage through the inner convolutions, thetemperature is further increased to the point Where vaporization of theless volatile fractions occurs. The hottest portion of all is theportion 93 of the vaporizing coil which lies in the direct path of theflame and which leads directly to the discharge end of the coil. Sincethe aerosol is progressively raised to the point of maximum temperatureand maximum vaporization just prior to discharge, and since the volocityof discharge varies with the heat which is applied, the presentconstruction minimizes the possibility that the aerosol will bedeteriorated by subjecting it to excessive temperatures. This isparticularly important when employing aerosol liquids containingpyrethrins which may be broken down when subjected to temperaturesgreater than, say, 600' F. The carrier liquid should preferably consistof fractions having a vaporization range of which is safely below thepoint at which a breaking down of the active ingredients may take place.For example, where pyrethrins are used, a carrier should be selectedhaving components which vaporize between 450 F. and 550 F.

Not only does the present device tend to protect heatsensitiveinsecticides or the like from overheating, but studies indicate that theoperation within the vaporizing coil is such as to promote formation offog droplets of optimum size. Thus the low boiling point fractions,because of the progressive heating, tend to be vaporized first. Thevapor thus formed propels the remaining, higher boiling point fractions,which are still in liquid form, through the tube at high velocity andwith a high degree of turbulence, breaking the liquid up into tinydroplets. Such droplets in turn suifer vaporization as highertemperatures are reached, further increasing the velocity andturbulence. Depending upon the ratio of heat to amount of aerosol liquidflowing, and upon the length and diameter of the tube, this process isin the present device, carried to a degree where the resulting dropletshave a range of between 10 and 12 microns which has been found to beoptimum. It is possible that a certain proportion of droplets in thisrange are formed by vapor condensation after ejection. Droplets of suchsize remain air borne for long periods and are thus able to penetratewherever air can penetrate and yet the droplets are, predominately, of asize large enough to be effective when brought into contact with anycommon insect. The low boiling point vapors upon ejection may recondenseinto droplets having a size which may lie below the above range, butsuch recondensed material forms only a small proportion of the total andhence is not particularly significant.

While the temperature of the effluent is maximum just prior todischarge, it is immediately cooled upon striking the atmosphere so theeffluent, as little as a foot or so away from the nozzle, may be termedcool.

Operation is simplicity itself. The gas valve 30 is turned on byunscrewing it a predetermined amount, say one turn. The flame islighted. The aspirating openings 81 may be covered by the fingertips tofacilitate lighting and warmup. When the temperature of the coil is highenough to produce vaporization, which takes to seconds, the trigger ispressed to produce copious volumes of a fog. The device may be usedwithout further adjustment until a falling off in the amount of fogindicates replenishment of the aerosol tank is necessary. The device iscapable of operating successfully even though the temperature and hencepressure of the fuel tank drops due to boil off of the liquid fuelbecause the fuel rate and insecticide rate both vary in the samedirection upon variations in pressure. However, if it is desired tosubstitute a fresh tank, at ambient temperature, this is but a simplematter of twisting one tank out, another in. No trained operator isneeded and the device may be operated safely by the average householder.

When it is desired to terminate the flow for a short time, the triggeris released. While this will of course cause the temperature of the coilto go up, subsequent pressing of the trigger, releasing aerosol liquidinto the coil has a quenching eifect so that the temperature isimmediately and automatically restored to the proper operating range.For longer standby periods, the gas valve may be turned down.

It is found that the volume of fog produced by the present device inspite of its portability and compactness nevertheless approaches thevolume produced by much larger vaporizing machines. Thus the relativelysmall hand held device, having a 15 inch maximum dimension and weighingabout eight pounds fully loaded, is capable of generating up to 3300cubic feet of fog each second. As a measure of efficiency the device iscapable of converting a single gallon of insecticide into approximately6 /2 million cubic feet of pest-killing fog.

Use of the device is not restricted to the out-of-doors. On thecontrary, because of its safety, portability and compactness, the devicemay be used indoors, especially for the purpose of injecting theefliuent through small cracks and openings. Sufiicient pressure andvelocity are developed at the nozzle so that the fog is literallypumped" into an enclosed space, with the products of combustion beingsafely diverted as described.

While the present fogging device is particularly suited for use withinsecticide, it will be understood that it is not limited thereto butmay be used for dispensing various substances for a wide variety ofpurposes including fumigants, deodorizers and bird and animalrepellants, to name a few.

Conveniently, propane or similar liquified hydrocarbon available incharged tanks of the type illustrated may be used as the fuel.

As to materials of construction, any heat resistant metal may be usedfor the burner tube and coil. However, metals should not be used in thecoil which have a catalytic effect upon any component of the aerosolliquid being used.

In the following claims the term burner tube has been used forconvenience to designate means defining a combustion chamber; however,it is to be understood that the term is not necessarily limited to useof a tube or cylinder whether horizontally or vertically disposed, butshall be broadly construed to cover equivalent enclosures which maydiffer therefrom in specific geometric shape. Moreover, where the outercoil convolutions are spaced so close together as to form a chamber toconfine the fiame, it will be apparent to one skilled in the art thatthe outer surfaces of such convolutions perform the function of theburner tube and can, accordingly, be considered to be the burner tubefor the purpose of reading the claims. a

This is a continuation of application Serial No. 29,429 filed May 16,1960, now abandoned.

We claim as our invention:

1. In an aerosol dispenser the combination comprising a burner tube, avaporizing coil in said burner tube and occupying a substantial portionof the length thereof, said vaporizing coil having an inlet end and adischarge end together with means for supplying aerosol liquid to theinlet end under pressure, a disk at one end of said tube and having aburner nozzle centered therein, a stem on said disc for supplyingcombustible gas to the nozzle for heating of the vaporizing coil, ahandle secured to the stem and means having aspirating openings in saidstem for aspirating combustion air to said burner thereby to maintainthe handle at a cool operating temperature.

2. In an aerosol dispenser the combination comprising a horizontalburner tube, a vaporizing coil in said burner tube having an inlet endand a discharge end, means for supplying aerosol liquid to the inletend, a valve body under said tube and in heat transferring relation withthe latter, a handle on said valve body for manually supporting thedispenser, a burner nozzle in said tube adjacent said handle, meansincluding a tank of liquified combustible gas secured to the valve body,means defining a gas passageway in the valve body interconnecting thetank and the burner nozzle, said valve body being of good conductingmetal and in good heat transferring relationship with respect to saidhandle so that the handle and valve body are maintained at a safely lowtemperature by the change of state of the liquified gas andnotwithstanding transfer of heat from the adjacent burner tube.

3. In an aerosol dispenser the combination comprising a frame, a burnertube mounted thereon, a vaporizing coil in said burner tube having aninlet at one end and having a discharge nozzle at the other end, meanssecured to the frame for supplying liquid aerosol under pressure to theinlet end of said vaporizing coil, means secured to the frame fordelivering combustible gas to said burner tube for combustion therein sothat the aerosol liquid is progressively vaporized to vapor form fordischarge from the nozzle of the vaporizing coil, said burner tubehaving vents for escape of the products of combustion, a handle securedto the frame, valve means in said frame at the inlet end of thevaporizing coil for controlling admission of aerosol liquid to saidcoil, and valve means in said frame for controlling the flow ofcombustible gas to the burner tube.

4. In an aerosol dispenser the combination comprising a burner tube, avaporizing coil in said tube and having an inlet end and a dischargeend, means for supplying aerosol liquid to the inlet end of the coil,means for pressurizing the aerosol liquid supplied to the inlet end ofthe coil, a burner nozzle in said burner tube, means for deliveringcombustible gas to said burner nozzle under pressure so that thecombustion thereof vaporizes the aerosol liquid in said coil fordischarge from the discharge end thereof in vapor form, and means forcoordinating the pressure of the combustible gas with the pressure onthe liquid so that the rate of flow of the aerosol is varied inaccordance with the amount of heat liberated in the burner tube.

5. In an aerosol dispenser the combination comprising a burner tube, avaporizing coil in said tube and having an inlet end and a dischargeend, a tank of aerosol liquid having a dip tube connected to the inletend of the coil, a burner nozzle in said burner tube, means including agas supply line for delivering combustible gas to said burner nozzleunder pressure so that the combustion thereof vaporizes the aerosolliquid in said coil for discharge from the discharge end thereof invapor form, and means for connecting the gas supply line to the tank ofaerosol liquid for pressurizing the latter so that the rate of flow ofthe aerosol liquid into the coil is coordinated with the amount of heatliberated in the burner tube.

6. In an aerosol dispenser the combination comprising a burner tube, avaporizing coil in said tube and having an inlet end and a dischargeend, a tank of aerosol liquid connected to the inlet end of the tube, atank of liquified gas, a burner nozzle in said burner tube having anorifice and having a gas supply line connecting the same to the tank, agas valve in said line adjacent said tank, and means for connecting thegas supply line to the tank of aerosol liquid so that the pressure fromthe line forces the liquid into the coil for vaporization and at a ratedepending upon said pressure.

7. In an aerosol dispenser the combination comprising a burner tube, avaporizing coil in said tube and having an inlet end and a dischargeend, a tank of aerosol liquid connected to the inlet end of the tube, atank of liquified gas, a burner nozzle in said burner tube having anorifice and having a gas supply line connecting the same to the tank, agas valve in said line adjacent said tank, means for connecting the gassupply line to the tank of aerosol liquid so that the pressure from theline forces the liquid into the coil for vaporization and at a ratedepending upon said pressure, and a check valve in said connecting meansfor preventing reverse flow into the gas supply line when the gas valveis turned off.

8. In an aerosol dispenser the combination comprising a burner tube, avaporizing coil in said tube and having an inlet end and a dischargeend, a tank of aerosol liquid connected to the inlet end of the tube, atank of liquified gas, a burner nozzle in said burner tube having anorifice and having a gas supply line connecting the same to the tank, agas valve in said line adjacent said tank, means for connecting the gassupply line to the tank of aerosol liquid so that the pressure from theline forces the liquid into the coil for vaporization and at a ratedepending upon said pressure, and a spring biased check valve in saidconnecting means having a spring pressure which is suflicient toestablish a pressure differential between the gas line and the tank ofliquid,

9. In an aerosol dispenser the combination comprising a burner tube, avaporizing coil in said tube and having an inlet end and a dischargeend, a tank of aerosol liquid having a dip tube connected to the inletend of the coil, a burner nozzle in said burner tube, means including agas tank and gas line for delivering combustible gas to said burnernozzle, means for pressurizing the tank of aerosol liquid at a pressurecoordinated with the pressure in the gas line, and means defining arestricted metering orifice associated with the dip tube for meteringthe flow of the aerosol liquid.

10. In an aerosol dispenser intended for hand support the combinationcomprising a horizontal burner tube having a front end and a rear end, avaporizing coil in said burner tube occupying a substantial portion ofthe length thereof, said vaporizing tube having an inlet end and adischarge end, a burner nozzle at the rear end of said burner tube, saidburner tube having vents distributed along the length thereof forvertical discharge of the products of combustion, a pistol grip handleat the rear end of said burner tube for supporting the latter, anelongated horizontally arranged valve body spaced below the burner tubeand secured to said pistol grip handle, a tank for gas and a tank foraerosol liquid arranged side by side and secured to the underside of thevalve body, said valve body having porting so that gas is supplied fromsaid gas tank to said burner nozzle and so that said aerosol liquid issupplied from said aerosol tank to the inlet end of said vaporizingcoil.

11. In an aerosol dispenser intended for hand support the combinationcomprising a horizontal burner tube having a front end and a rear end, avaporizing coil in said burner tube occupying a substantial portion ofthe length thereof, said vaporizing tube having an inlet end and adischarge end, a burner nozzle at the rear end of said burner tube, saidburner tube having vents distributed along the length thereof forvertical discharge of the products of combustion, a pistol grip handleat the rear end of said burner tube for supporting the same, anelongated horizontally arranged valve body spaced below the burner tubeand secured to said pistol grip handle, a tank for gas and a tank foraerosol liquid arranged side by side and secured to the underside of thevalve body, said valve body having a gas valve interposed between thegas tank and the burner for controlling the flow of gas to the latter,said valve body further having a digitally operated control valveinterposed between the aerosol liquid tank and the inlet end of saidvaporizing coil for controlling the flow of aerosol liquid to thelatter.

12. In an aerosol dispenser the combination comprising a horizontalburner tube of heat resistant material forming a combustion chamberhaving a front end and a rear end, a vaporizer coil in said tubeextending horizontally over a substantial portion of the length thereofhaving an outlet terminating at the front end of the tube and having aninlet, means for supplying to the inlet end of said coil an aerosolliquid under pressure, means including a burner for injecting into therear end of the tube a mixture of air and combustible gas for combustionthereof Within the confines of the vaporizing coil and in direct contactwith the latter thereby to progressively vaporize the aerosol liquid tovapor form, said burner tube having Vent means for lateral and upwarddischarge of the products of combustion but having an imperforate cap 11 secured to the front end of the tube for substantially blocking theproducts of combustion against forward discharge, the outlet end of thecoil being extended forward- 1y beyond the cap and substantially sealedwith respect to the latter for discharge of the aerosol vapor axiallyaway from said tube and in a horizontal direction which is substantiallyat right angles to the direction taken by the products of combustion,said coil terminating in a straight run tip portion projecting beyondthe cap a sufiicient distance and of such limited and constant diameteras to enable insertion of said tip portion into cracks and en- 12 closedspaces for discharge of vapor therein free of contamination by theproducts of combustion.

References Cited in the file of this patent UNITED STATES PATENTS1,497,428 Braun et a1. June 10, 1924 1,614,015 Neuls Ian. 11, 19272,402,402 Hickman June 18, 1946 FOREIGN PATENTS 429,493 France July 19,1911

12. IN AN AEROSOL DISPENSER THE COMBINATION COMPRISING A HORIZONTALBURNER TUBE OF HEAT RESISTANT MATERIAL FORMING A COMBUSTION CHAMBERHAVING A FRONT END AND A REAR END, A VAPORIZER COIL IN SAID TUBEEXTENDING HORIZONTALLY OVER A SUBSTANTIAL PORTION OF THE LENGTH THEREOFHAVING AN OUTLET TERMINATING AT THE FRONT END OF THE TUBE AND HAVING ANINLET, MEANS FOR SUPPLYING TO THE INLET END OF SAID COIL AN AEROSOLLIQUID UNDER PRESSURE, MEANS INCLUDING A BURNER FOR INJECTING INTO THEREAR END OF THE TUBE A MIXTURE OF AIR AND COMBUSTIBLE GAS FOR COMBUSTIONTHEREOF WITHIN THE CONFINES OF THE VAPORIZING COIL AND IN DIRECT